The invention relates to a new and improved flat-storable blast hole liner of the type used for lining blast holes and, more particularly, to such a liner of the type having a pocket arrangement for holding weight materials to facilitate insertion of the liner unit into a blast hole.
In the mining industry where the mineral lies substantially below ground level, blast holes are bored for receiving explosive charges. Detonating of the charges breaks up the hard material surrounding the holes. An ammonium nitrate-fuel oil mixture (commonly known as "ANFO") is often employed as the explosive. Water (eg, from rain or ground water sources) has a deleterious effect upon the explosive quality of this material, however, and accordingly it is common practice to insert waterproof plastic liners into the blast holes for holding the explosive charges. Such liner units may be equipped with pouch arrangements at the lower ends thereof for receiving rock "cuttings" or like weighting material to facilitate the lowering of the liner units into the blast holes. Liners of this general type are described in commonly owned U.S. Pat. Nos. 3,760,727 and 3,881,417, as well as in Canadian Pat. No. 667,051.